Heavy reformate (HR), containing mainly C9+ aromatics, is the fraction that remains after extraction of the more valuable BTEX (benzene, toluene, ethylbenzene, xylene) fraction from the catalytic reformate or the pyrolysis gasoline. Traditionally this fraction was directly added to the gasoline pool. However, due to the restriction of the benzene content in gasoline by environmental regulations, it is important to find alternative ways of upgrading this stream into other valuable products. One option is to convert the heavy aromatics in the heavy reformate into xylenes. Demand is growing faster for xylene derivatives than for benzene derivatives. Therefore, a higher yield of xylenes at the expense of benzene yield is a favorable objective. Heavy reformate may be converted into xylenes and other compounds by means of dealkylation of the C9+ alkylaromatics or by transalkylation of these compounds with benzene or toluene.
Heavy reformate may also be converted into xylenes by dealkylation of the C9+ alkylaromatics to benzene and toluene, and further transalkylation of these compounds formed by dealkylation with other C9+ alkylaromatics present in the feed. Regardless, these means to produce xylenes by simultaneous dealkylation and transalkylation have limited efficiency, because of the sequential nature of the conversion reaction process where products of a first reaction are utilized in a second reaction.